This invention relates to an engine system for increasing net thermal efficiency of main ship engines, in particular to an engine system for increasing net thermal efficiency of two-cycle Diesel engines.
For increasing net thermal efficiency, U.S. patent application Ser. No. 438,647, now U.S. Pat. No. 4,531,480, addressed the problem of pressure produced by gas expansion in piston power transmission apparatus of conventional internal combustion engines.
In other words, the engine disclosed in said invention was designed to increase the force acting on the cross-sectional area of the piston, thereby enhancing the power output of the engine system by applying basic principles of fluid mechanics and taking into account the difference of cross-sectional areas between the top and bottom pistons. Further, oil in the hollow chamber is used for producing pressure by means of cylinder functioning as an oil pump during the power stroke.
Therefore, the constant pressure produced by gas explosion is applied to the top piston. Then the force exerted on the cross-sectional area of the top piston is transferred through the oil chamber and then converted to mechanical energy forcing the bottom piston downward. Thus the force exerted on the cross-sectional area of the bottom piston is multiplied in proportion to the cross-sectional areas of the top and bottom pistons. But it is noted that the stroke distance of the bottom piston is not sufficient to reach BDC.
Accordingly, the engine disclosed in said invention provides a ring-type piston in the external chamber of the upper cylinder block.
The ring-type piston is operated to compensate for the insufficient stroke distance as soon as the pressure in the cylinder chamber drops below the pressure of the outer compressed air storage.
Consequently the greatly increased force is applied to the bottom piston and is transferred to the crank shaft by means of the connecting rod.
However in the cited invention, the pumping of oil to produce additional power involves a great deal of sliding motion of the top piston, therefore temperature rise of the oil is inevitable despite the presence of a water jacket around the cylinder block for cooling.
Furthermore, oil leaks into the combustion chamber despite the presence of a piston ring, oil ring and seal ring installed within the ring grooves of the top piston and despite precision tooling of the top piston and cylinder wall.
As is obvious, there are many problems with said invention including incomplete combustion, atmospheric pollution, overheating, oil leakage, etc.
Accordingly, the object of this invention is to provide an engine system for ships for increasing net thermal efficiency of two-cycle diesel engines.
The main engine body of this invention is comprised of a main combustion chamber for generating power and a power transmission apparatus for transferring the greater power produced in the main combustion chamber to the power crank shaft.
Another object of this invention is to provide a swash plate-type stirling engine and a single-stage screw-type compressor for compressing air by utilizing heat of exhaust gas ignited in the main combustion chamber.
A further object of this invention is to provide a compressed air control device for properly adjusting the application of compressed air to the top piston of power transmission apparatus.
A further object of this invention is to provide a booster for supplying oil pressure to the external chamber of the power transmission apparatus, in which oil pressure is produced by a compressed air storage in order to compensate for insufficient oil pressure of the power cylinder.
A further object of this invention is to provide a long rod between the combustion chamber piston and pumping piston so as to directly transfer the explosion pressure of the combustion chamber to the pumping piston in the power transmission apparatus.
A further object of this invention is to provide four orifices which act as a buffer spacer in the rod guide by the circulation of oil in the power cylinder.
In order to achieve the above-mentioned objects, this invention comprises a main combustion engine, a power transmission apparatus, one or more swash plate-type stirling engines, a single-stage screw-type compressor a compressed air storage, a booster, an accumulator, and a compressed air control device.
Said combustion engine has a combustion chamber piston which works with a sliding and reciprocating motion in the combustion chamber, a long rod which is connected to the bottom of said combustion chamber piston, and two upper connecting rods which are connected between said long rod and two cranks in the combustion chamber. The power transmission apparatus comprises a pumping piston, a power piston, a pumping cylinder block, and a power cylinder block. Said pumping piston in the pumping cylinder works with a sliding and reciprocating motion which is timed with the same stroke as the combustion chamber piston of the main combustion engine, and said power piston works with a sliding and reciprocating motion which is timed with the same stroke is the pumping piston, and a rod guide which shields an end of said long rod is fixed to the center of the power piston, and said power piston is connected to a power connecting rod which transfers rotation power to the power crank shaft, and a pumping cylinder block is composed of a pumping cylinder chamber and an external chamber, and the intake and exhaust passages for intake and exhaust of compressed air to the top of pumping piston and oil reciprocating passages for holding the oil pressure constant within the oil chamber are formed in the pumping cylinder block. In said pumping cylinder chamber the pumping piston works with a sliding and reciprocating motion and the external chamber is formed as a circular column around the pumping cylinder, and in the power cylinder chamber of the power cylinder block the power piston works with a sliding and reciprocating motion, further the cross-sectional area of the power piston is greater than that of the pumping piston.
Said swash plate-type stirling engine is attached to the exhaust gas outlet of the main combustion engine and is operated by utilizing exhaust gas heat of the main combustion engine.
Said single-stage screw-type compressor which is connected to said swash plate-type stirling engine is used to generate a great deal of compressed air.
Said compressed air storage is used to store a great deal of compressed air generated by said single-stage screw-type compressor.
Said booster is used to generate greater oil pressure by the compressed air of the said compressed air storage.
Said accumulator which is operated by compressed air of said compressed air storage is used to provide constant oil pressure to said power transmission apparatus.
Said compressed air control device is used for intake and exhaust of compressed air to the pumping piston of said power transmission apparatus.